Flow diversion complications: the impact of enzymatic digestion on aneurysmal walls.*

Giant intracranial aneurysms are a life-threatening condition, where the standard out-patient treatment involves the placement of a fine-mesh stent that diverts blood flow away from the aneurysm. However, 20% of these treatments results in a delayed aneurysm rupture (DAR). While hemodynamic simulations of flow diversion suggest an increase in pressure at the sight of the aneurysm, a non-mechanical hypothesis has been proposed where upregulated matrix metalloproteinases (MMPs) at the aneurysm can occur as an inflammatory response to the treatment, which then result in a DAR. Pathological vascular remodeling of the aneurysmal walls has been correlated to upregulated MMPs, but the impact of MMPs on the arterial walls is not yet well understood. Porcine carotid arteries were prepared and treated with MMP-1, MMP-2, MMP-9, and MMP-1/2/9 for point-by-point indentations by colloidal probes via atomic force microscopy. The Young's moduli of the tunica media were extracted from stress-strain curves to investigate the impact of MMP digestion at various concentrations and to offer new insight in flow diversion complications. Results and limitations from the study will be presented and discussed.